The present invention generally relates to a storage system and a data erasing method, and can be particularly applied to a storage system equipped with a cache memory.
In a storage system where a server and a storage apparatus are connected, if data is written from the server in file units into a plurality of hard disk drives in the storage apparatus, the erasure of data must also be conducted in file units.
When erasing data, in order to prevent the data to be erased from remaining in the hard disk drives as magnetic information, it is necessary to write arbitrary data over the data to be erased.
For instance, Japanese Patent Laid-Open Publication No. 2007-11522 proposes a method of erasing data to be erased in data units by writing arbitrary data over the data to be erased when a host issues a complete erasure command for erasing the data to be erased stored in the hard disk drive of the storage apparatus.